don't worry. consult a doctor and talk about your weight problem. don't go for all weight losing activities all of a sudden.
a chance will be given to you and losing weight is not that easy.only 2-4 kg weigh change can made in such time but not much.
ideally it is better to lose 12 kg in 6 months so you also do not have health problems.start exercising with easy activities and within 3 months move to some strenous exercises so you lose weight.
losing weight by diet is of no help , you will again gain weight within no time.

i remember a case of a candidate who was overweight and has serious issue with fpsc,probably a court case. but i cannot remember exact details and its conclusion.
may be someone from CSP may guide you in this matter
best of luck

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